The healing power of writing lays in the way it allows us to create stories based on our own awkwardnesses. Fiction allows you to create ANY story based on your own experience and make it take any turn you are too afraid to admit to yourself you wished it followed.
Creative writing is based on having a time and a space to put our ideas down on paper. When used as a therapeutical tool, you are allowed to destroy what you have written down, especially if you've let your anger loose. In the absence of time, you can still let your feelings out as you create the story in your mind, purposely.
I wouldn't suggest you harm a loved one in your story but I would definitely encourage you to stop them from doing or saying what hurts you. If it's too painful to write a short story about you and that person, get out of the story and write about characters A and B, inspired by this particular situation that feels too awkward to even think about. You will be surprised as to how much you can discover about your own feelings and about how you would feel if things were different.
In my own experience, I've felt the healing effect of realising that there was a lot of drama in my own mind. In some cases, the simple exposition of a situation can make you understand that what bothers you is no longer there or that you are a more mature person than when you felt aggravated the first time and you can let go of a resentment that only harms you.
Why don't you give it a try? Next time you take time to walk or you get stuck in traffic, don't allow your mind to wander. Take control of your own thoughts and deal with that issue that bothers you in a proactive way. Have that conversation you've been avoiding, create those circumstances that have been missing and let me know if you have felt the powerful healing effect of creating your own story.
